Proof of employment

Most potential landlords will accept pay stubs or an offer of employment letter as proof that you're employed. Some will require tax records to show how much income you've made over the past few years. If you're a contractor, then you'll need to find another way to prove that you can pay the rent. This might mean showing your contract with your clients or providing statements from your business account or personal bank account, or your most recent tax returns.

Credit check

Larger rental agencies or complexes will probably do a credit check, so you'll need to have your social security number (or SIN if you're in Canada) with you. Make sure when you give it out that the person you're giving it to works for a legitimate company. Don't give it to individuals or landlords who demand it.

Photo Identification

Most potential landlords or rental agencies will ask for proof of identification to make sure you are who you say you are. Usually, a driver's license will suffice or a passport - anything with a photo and that's been government issued regardless of what country you're from.

List of past addresses

Most rental applications will require at least three references of past landlords with contact details. If you move a lot, then you'll need to make sure you can provide the most recent rental names, addresses, and contact information.

Most recent tax return

Some landlords require a copy of your most recent tax return. This provides them with information on earnings over the past year. A tax return may be a replacement for employment records, or if you're unemployed, the return will show how much you earn in a year and whether you'll be able to ​cover the rent and other costs such as down payments or security deposits.

Banking information

Make sure you protect yourself by not revealing your bank account number. Provide your potential landlord with printed copies so you can black out portions that are private information and never provide originals. Always take photocopies or electronic copies (again, with personal information removed).

Reference letters

In case you don't have enough to back-up your application, it's a good idea to collect reference letters from past landlords or current employers. This is particularly true if you have pets. A new landlord wants to make sure you're a responsible pet owner and often that can be proven through past or current landlord either through a reference letter or by direct contact.

Proof of Residency

If you're not a citizen of the country you're moving to, most rental agencies will ask for your legal right to be in the country. Recently, we had to present our Green Cards to a new landlord before they'd rent to us. Some rental apartments will be more strict about needing to show a visa or other proof than others. Single homes, smaller apartment buildings or sublets probably won't ask for this, but just in case, have your documentation ready.